Fabrication and characterization of 3-dimensional electrospun poly(vinyl alcohol)/keratin/chitosan nanofibrous scaffold.

Layer-by-layer three-dimensional nanofibrous scaffolds (3DENS) were produced using the electrospinning technique. Interest in using biopolymers and application of electrospinning fabrication techniques to construct nanofibers for biomedical application has led to the development of scaffolds composed of PVA, keratin, and chitosan. To date, PVA/keratin blended nanofibers and PVA/chitosan blended nanofibers have been fabricated and studied for biomedical applications. Electrospun scaffolds comprised of keratin and chitosan have not yet been reported in published literature, thus a novel nanofibrous PVA/keratin/chitosan scaffold was fabricated by electrospinning. The resulting 3DENS were characterized using fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential scanning colorimetry (DSC), and thermogravimetric analysis (TGA). Physiochemical properties of the polymer solutions such as viscosity (rheology) and conductivity were also investigated. The 3DENS possess a relatively uniform fibrous structure, suitable porosity, swelling properties, and degradation which are affected by the mass ratio of keratin, and chitosan to PVA. These results demonstrate that PVA/keratin/chitosan 3DENS have the potential for biomedical applications.

Prediction of applied pressure on model lower limb exerted by an air pneumatic device.

Air pneumatic compression is a concept used for management of venous disease, including oedema. A typical air pneumatic compression device (PCD) consists of an inflatable sleeve composed of either single or multiple pressure chambers that encircle a limb. The aim of this research was to develop a mathematical model to predict the pressure applied by an air pneumatic device to an irregular cross-sectional lower limb manikin. The radius of curvature at any cross-section of the lower limb (i.e. calf (gastrocnemius), tibial crest (anterior edge of the tibia bone)) is irregular, and differs amongst individuals and populations. The effectiveness of air pneumatic devices is difficult to predict with these irregular cross sections. A theoretical model was developed to calculate pressure applied by compression sleeves on a lower leg manikin and results compared against experimental pressure exerted on the manikin by a silicone-based PCD. This prediction was made at each of three positions. The theoretical model developed based on elliptical shaped forms predicted the pressure more accurately for the ankle to above ankle position, whereas the model based on circular shaped forms predicted the pressure more accurately for below the calf to below the knee position. Refinements to the theoretical model to predict the pressure applied by PCD are recommended.

Understanding Stress-Strain Behavioral Change in Fabrics for Compression Bandaging.

Bandages are common in many health-related treatments, including management of edema of the lower limb where they may remain in place for several days. The behavior of 2 bandage fabrics was investigated after exposure for up to 5 days to a multiaxial extension laboratory setup on a tensile tester in compression mode. The fabrics were extended 20% and remained under that machine setting. Stress-relaxation over time was determined by analyzing the rate of change over 24 hours and over 5 days. Most change, a rapid drop in force, occurred during the first 15 minutes; thereafter, for the next 12-hour period, a slower rate of decrease was observed. Both fabrics continued to relax gradually during the next 12 hours and continued to do so for up to 5 days. Little further change was evident during the last 12 hours or so. This phenomenon suggests that rewrapping may be appropriate (albeit not practical) after 12 hours of compression therapy to optimize the compression given to the lower leg. Relaxation behavior of these 2 fabrics can be explained using the generalized Maxwell-Wiechert model.

Textile-based compression therapy in managing chronic oedema: Complex interactions.

BACKGROUND: Compression is a common therapy for management of chronic disease, including oedema of the lower limb. Modern compression interventions exert pressure on the lower limb through use of one or more materials which exert pressure against the limb over time. Where these materials are textiles, they range from elastic to inelastic, and are produced using knitting, weaving, or other textile technologies which can be manipulated to control performance properties. Thus, understanding of both the materials/textiles and the human body is needed if the most appropriate compression device and treatment strategy is to be used. Neither is independent of the other. This review aims to enhance understanding of critical textile performance properties and how selection of textiles may affect treatment efficacy when managing chronic oedema of the lower limb. METHOD: Relevant papers for review were identified via PubMed Central® library, and Google Scholar using keywords associated with textile-based treatments of the oedematous lower limb and wider interdisciplinary factors. RESULTS: Assessment of the disorder, the severity of oedema, and location of fluid accumulation are required to inform treatment of chronic oedema. While the need to understand the patient is well established (e.g. age, sex, body mass index, skin thickness and colour, patient compliance with treatment), information about preferred compression systems and material structures, and inherent properties of these, is generally lacking. CONCLUSION: Greater detail about materials used (e.g. fabric structure, number and order of layers, fibre content) and patient diagnosis (e.g. underlying cause, severity, location of oedema; patient age and sex; evidence of compliance with treatment; pressure exerted; lower leg shape, size, and properties of the tissue) is needed to facilitate advances in efficacy of compression treatment. Reduced limb swelling with a textile-based treatment occurs simultaneously with changes to the textile itself. Textiles cannot be considered inert.

Layering garments during rest and exercise in the cold (8°C): wearer responses and comparability with selected fabric properties.

How garments contribute to performance of the clothing system during wear is of interest, as is understanding the value of using fabric properties to inform end-use characteristics. To investigate the influences of layering upper-body garments, four fabrics were used to construct two first-layer garments (wool and polyester) and two outer-layer garments (wool and membrane laminate). Over six sessions, 10 moderately trained males wore each first-layer garment as a single layer and in combination with each outer-layer garment while resting, running and walking in cold environmental conditions (8 ± 1°C, 81 ± 4% RH). Here, the type of garment arrangement worn (fabric type or number of layers) had little influence on heart rate, core body temperature and change in body mass. Weighted mean covered skin temperature was warmer and weighted mean next-to-skin vapour pressure was typically higher (following the onset of exercise) with two layers versus one. Differences among fabrics for individual properties were typically overstated compared to differences among corresponding garments for physiological and psychophysical variables under the conditions of this study. These findings inform the interpretation of particular fabric properties and highlight issues to be acknowledged during development/refinement of fabric test methods. PRACTITIONER SUMMARY: We examined the way in which selected fibre, fabric and garment (layering) characteristics contribute to performance of the clothing system during wear under cold conditions. Selected properties of the constituent fabrics were found to provide limited insight into how garments perform during wear under the conditions of this study.

Variation in the ordered structure of complexes between CD154 and anti-CD154 monoclonal antibodies.

The cell surface co-stimulatory protein CD154 (CD40L) is a target for monoclonal antibody (mAb) inhibitors of T-cell mediated immune diseases. This protein, like most other members of the TNF ligand family, forms homotrimeric complexes on the cell surface and in solution, with a three-fold axis of symmetry. We find that several different anti-CD154 monoclonal antibodies form distinctive complexes with soluble CD154. These soluble complexes have been analyzed using size exclusion chromatography, static and dynamic light scattering, and electron microscopy and shown to consist of caged structures of various geometries. The cell surface complexes have been analyzed by confocal microscopy and, depending on the mAb, remain as small, separate complexes or form large aggregates. The formation of these complexes in solution is likely to have an impact on measures of affinity, while the cell surface complexes could affect binding potency and provoke other biological effects.